>However,
 > I've corresponded with parents of babies who are allergic to casein,
>a necessary component of ALL milks, inclding breastmilk.  (I think I
 > corresponded with parents of both such babies alive in the world
>today   So anyway, it IS possible.

Casein is not all identical. According to Lawrence, "The term casein
includes a group of milk-specific proteins characterized by ester-bound
phosphate, high-prolinecontent, and low solubility at pH 4.0 to 5.0. . .
There are physiochemical differences between human and cow caseins."
(from Breastfeeding: A Guide for the Medical Profession 4th ed. 1994,
p.110) This doesn't prove that a baby could never be allergic to his
mother's casein, but since it is not identical to cow casein, allergy to
one form doesn't necessarily mean allergy to all.

Catherine Mallon
Sherwood Park, Alberta, Canada